Zinc

Zinc: Overview

Zinc is an essential trace mineral that occurs in greater amounts than any other trace mineral except iron. Its functions are varied and numerous, including synthesis of cholesterol, protein and fats, releasing vitamin A from the liver, assisting the immune system and cell growth, being required for vision, taste perception, prostrate reproductive health and insulin function, metabolizing alcohol, and protecting against copper and heavy metal toxicity such as cadmium and lead.

Note: Food processing removes a large amount of zinc as well as other trace elements. For example, whole brown rice has more than 4 times the zinc that polished white rice has. Molasses has 42 times more zinc than an equal amount of white sugar. By weight, the germ part of wheat has 15 times more zinc than can be found in white flour.

Various forms of zinc exist, essentially in two forms: salt, and chelated. Salt forms of zinc include gluconate, citrate, picolinate and others. While various reports have touted the capabilities of certain salt forms to absorb better than others, proper chelated forms usually absorb better than salt forms. Supplements should take advantage of a combination of chelated and salt forms for maximum absorption.

Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement. It is found naturally, and is also manufactured by the fermentation of glucose, typically by aspergillus niger, but also by other fungi. In its pure form, it is a white to off-white powder. It can also be manufactured by electrolytic oxidation, although this is a more expensive process.

Very often, zinc is included in prostate health, as well as BPH products.

Function; Why it is Recommended

Zinc, in general, is considered an adjunct to the body's overall antioxidant system. For example, the important free-radical scavenging enzyme super-oxide dismutase (SOD) requires both zinc and copper for its activity.

Zinc plays a very important role in over 50 different proteins or enzymes in humans. These enzymes are critical for the immune system, overall cellular metabolism, control of protein synthesis and protection of membrane lipidperoxidation.

The popularity of zinc has increased recently as the use of zinc lozenges for colds have been researched and marketed. Zinc is also important for the proper health and function of the prostate.

Instructions

The RDA for zinc 15mg; the optimal daily intake is 30-50mg; the average daily intake in the U.S. is 10mg per day. Therapeutic doses are 30-350mg but care must be taken to avoid toxicity.

Copper, calcium, iron and phytates taken in large doses can interfere with (inhibit) zinc absorption and induce a deficiency, especially in pregnant women. People who take large doses of iron to correct anemia when they are already borderline zinc deficient can easily create a true zinc deficiency. Zinc should always be taken with copper in a 10 to 1 through 30 to 1 zinc to copper ratio.

One Suggested Supplementation Regime
During any period of supplementation the zinc taste test should be repeated at appropriate intervals and the subsequent dose of zinc adjusted up to the required level. In addition, it should be noted that when starting any programme of zinc supplementation the starting dose should always be a minimum dose of 15-25mg. This is then increased slowly in the following manner stopping at the required level as demanded by the results of the taste test.

In the first week: take one 15-25mg dose per day.

Second week: two 15-25mg capsules or tablets per day.

Third week: one 50mg dose per day.

Fourth week: two 50mg doses per day.

Fifth and subsequent weeks: three 50mg doses per day.

The reason for this protracted introduction is that zinc treatment, in the presence of zinc deficiency, may initially induce a feeling of fatigue or depression: a slow introduction reduces this possibility. This initial paradoxical response (zinc is normally stimulant in its action – by improving vigor and vitality) is not inevitable but if it does occur it may discourage the user from continuing the treatment. Continued use, after two to three weeks, will normally result in the expected improvement in vitality. Tiredness persisting beyond this time suggests the need for additional oil supplements or the anti-oxidant vitamins or minerals.

Zinc should be taken each day after food. If unusual tiredness occurs during the initial stages of treatment it should be taken at night before retiring to bed. In this way it will benefit any difficulty in sleeping and promote increased vitality the following day. Various zinc preparations may be used including possibly chelated zinc, zinc citrate, zinc picolinate, or zinc gluconate. Zinc sulfate is the most common (and cheapest) presentation but should be avoided due to the frequent occurrence of gastric irritation and dyspepsia. To avoid such a possibility, as a precaution, any zinc preparation should be taken after food. The most efficiently absorbed is the chelated form. This is where the zinc is combined with an amino acid, which assists in its absorption.

High doses of zinc (50mg per day or more) should also be accompanied by a small dose of copper. This is because a large amount of zinc in the diet will compete with, and reduce the absorption of, copper. It therefore becomes necessary to take a regular supplement of copper to prevent a state of copper deficiency developing. The appropriate dose of copper is 2-4mg per day. This single dose is all that is required whatever the dose of zinc used.

High doses of zinc will also tend to reduce the absorption of iron. This is not usually a problem but, in strict vegetarians, when the intake of iron is low, there may be a need to take a small, regular dose of iron to prevent the occurrence of iron-deficiency anemia.

Side-Effects

It is wise to go above 15mg only with a doctor's supervision because long-term zinc supplementation may interfere with the absorption of copper, another essential trace mineral. Signs of toxicity include diarrhea, nausea and vomiting.

Zinc at doses of 20mg and above may cause stomach upset and/or nausea so it should always be taken with food. Long-term zinc supplementation above 50mg has been shown to decrease HDLcholesterol and increase total cholesterol. This may be due to an induced copper deficiency. In addition, copper deficiency anemia can occur as well. Large doses of zinc may also promote folate deficiency.

Zinc gluconate may interfere with the absorption of antibiotics, so combinations may be unsafe.

On This Page

Zinc can help with the following:

Addictions

Low zinc status has been observed in 30% to 50% of alcoholics. Alcohol decreases the absorption of zinc and increases loss of zinc in urine. In addition, many alcoholics do not eat an acceptable variety or amount of food, so their dietary intake of zinc may be inadequate.

Circulation

The immune system is adversely affected by even moderate degrees of zinc deficiency. Severe zinc deficiency depresses immune function. Zinc is required for the development and activation of T-lymphocytes, a kind of white blood cell that helps fight infection. When zinc supplements are given to individuals with low zinc levels, the numbers of T-cell lymphocytes circulating in the blood increase and the ability of lymphocytes to fight infection improves.

Zinc can be used topically or orally to encourage wound healing and plays a well-documented role in wound healing. Although zinc is present in the body in only a small quantity, it is found in many tissues, including bone, skin, muscle, and organs. It is a component of DNA, RNA, and numerous enzyme systems that participate in tissue growth and healing. Zinc is crucial for protein synthesis and is a key part of the thymulin molecule which enables T-lymphocytes to mature.

Excess zinc can cause tissue injury and impaired wound healing [Cario et al. 2000]. However, relative zinc deficiencies, especially in the elderly, are common in the United States [Andrews et al. 1999].

Zinc should be taken at least 2 hours after copper or the antibiotic tetracycline.

Studies show that poor, malnourished children in India, Africa, South America, and Southeast Asia experience shorter courses of infectious diarrhea after taking zinc supplements. Amounts of zinc provided in these studies ranged from 4mg per day up to 40mg per day and were provided in a variety of forms (zinc acetate, zinc gluconate, or zinc sulfate). Zinc supplements are often given to help heal skin ulcers or bed sores, but they do not increase rates of wound healing when zinc levels are normal.

Diet

Vegetarians may need as much as 50% more zinc than non-vegetarians because of the lower absorption of zinc from plant foods, so it is very important for vegetarians to include good sources of zinc in their diet.

Vegetarians may need as much as 50% more zinc than non-vegetarians because of the lower absorption of zinc from plant foods, so it is very important for vegetarians to include good sources of zinc in their diet.

Digestion

A study involving zinc supplementation in inflammatory bowel disease illustrated the importance of taking adequate supplementation, but not too much. In this study, excess amounts of zinc caused tissue injury and impaired wound healing [Cario et al. 2000]. However, relative zinc deficiencies, especially in the elderly, are common in the United States [Andrews et al. 1999].

In a double-blind study on 18 patients, those taking zinc sulfate supplements had a gastric ulcer healing rate three times that of patients treated with a placebo. [The healing of gastric ulcers by zinc sulfate. Med J Aust 2(21): pp.793-6, 1975]

Environment / Toxicity

Zinc inhibits the uptake of cadmium and lead by various tissues in the body. Zinc is a well known antagonist to copper. It has been used to treat Wilson's Disease (in which there is an excess of copper).

Eyes / Ocular

Oral use of zinc has produced improvement in vision. Intravenous administration along with selenium have demonstrated benefits in the treatment of macular degeneration. According to researchers at Harvard University, however, zinc has shown mixed results. [Arch Ophthalmol 1988:106, pp.192-8]

Glandular

Hormones

Zinc should be given once testing confirms a low zinc or high copper level. Zinc and manganese allow for the normal storage of histamine in both basophils and the brain. During treatment, the largest tissues of the body – namely the liver and muscles – are flushed of their copper first so that the serum copper may rise to aggravate mental symptoms. If this occurs then the dose of zinc should be reduced for a two week period.

Supplemental zinc therapy (in capsules or tablets of 50mg of elemental zinc, 3 times daily, separated from food by at least 1 hour) was found to be an effective sole therapy in the long-term treatment of Wilson's disease. This study was a ten year follow-up of 141 Wilson's disease patients. Zinc helps block the absorption of copper and acts to remove accumulated copper from the body as well as prevent its accumulation. [J Lab Clin Med, 1998;132: pp.264-278]

Infections

Zinc lozenges have been found to be effective when locally applied to an inflamed throat. Lower dosages of zinc (10mg) with more frequent application are best, and may help avoid any nausea which might result from higher doses.

Inflammation

Sugar-free herbal-based lozenges fortified with vitamin C or zinc, a mineral that speeds healing, are very helpful. Lozenges increase saliva production and help soothe a dry, irritated throat. Take one lozenge every hour, as needed, for up to one week.

Male-Specific

Zinc supplementation has a clearly documented usefulness in shrinking an enlarged prostate. Research has shown that zinc and essential fatty acids are important to help prevent prostate problems that affect men as they grow older. Many studies confirm that a lack of these two nutrients in the diet could be associated with prostate enlargement.

Zinc has been found to inhibit the activity of 5-alpha reductase, the enzyme that irreversibly converts testosterone to dihydrotestosterone, a form which binds more avidly to the prostrate and stimulates greater growth. It also decreases prolactin secretion by the pituitary gland, thus decreasing its binding to the prostate, both of which prevent prostatic enlargement.

Metabolic

Kryptopyrrole is a reacting agent which combines irreversibly with active vitamin B6. The resulting molecule then chelates zinc, the combined product appearing in the urine. The whole syndrome is stress-induced so the susceptible patient, when stressed, quickly becomes vitamin B6 and zinc deficient.

Reproductive

Skin-Hair-Nails

Zinc is important in the treatment of acne. It is involved in local hormone activation, retinol binding protein formation, wound healing, immune system activity, and tissue regeneration. There have been inconsistencies in the results from studies using zinc as a treatment, but this may have been due to different forms of zinc having been used. If zinc insufficiency is suspected, use the more absorbable forms. Treatment may require up to 3 months of supplementation before good results are seen. Success or failure of zinc treatment of acne depends on whether a zinc deficiency is present. [Z Hautkr 1987:62(14): pp.1064, 1069-71, 1075]

One university study found that in subjects suffering from marginal zinc status, an enzyme involved in cell reproduction was uniquely impaired in the skin. Clinical experience has shown zinc supplementation to be particularly valuable in treating eczema, probably due to its being a common deficiency and its importance in delta-6-desaturase. Zinc may provide some benefit either orally or topically.

Zinc can help prevent the following:

Aging

Maintain adequate zinc status: Reduced levels of zinc are being linked to Alzheimer's disease. In one study, 38 elements were evaluated by neutron activation and mass spectrometry in the post-mortem brain tissue of eleven Alzheimer's patients and six controls. An increase was found in aluminum, silicon and calcium; a significant decrease was found in zinc and selenium. The lower level of zinc in all areas of the tissue studied correlates with reports indicating low serum levels of zinc in other dementia studies. [Reduction of Zinc and Selenium in Brain Alzheimer's Disease: Corigan, et al., Trace Elements in Medicine, 91;8(1): pp.1-5]

Tumors, Malignant

It was found that the copper to zinc ratio was significantly higher in patients with lymphoma or acute and chronic leukemias compared to control subjects. A person at increased risk of one of these cancers should check blood levels of copper and zinc to rule out abnormalities and make adjustments accordingly. Since zinc and copper are antagonistic, and zinc deficiency is relatively common, supplemental zinc is often used to improve this ratio. Zinc helps block the absorption of copper and acts to remove accumulated copper from the body as well as prevent its accumulation. [Rev. Invest. Clin, Nov-Dec. 1995;47(6): pp.447-52]

Your body is a highly complex, interconnected system. Instead of guessing at what might be wrong, let us help you discover what is really going on inside your body based on the many clues it is giving.